Antennal Morphology and Sexual Dimorphism of Antennal Sensilla in Callitettix versicolor (Fabricius) (Hemiptera: Cercopidae)

The rice spittlebug Callitettix versicolor (Fabricius) is an important pest of rice and maize in South Asia and causes severe economic damage. To provide background information for chemical ecology studies, the fine morphology of antennae and the types and distribution of the sensilla on the male and female antennae of Callitettix versicolor (Fabricius) are investigated by means of scanning electron microscopy (SEM). Results show that the antenna is filiform and composed of three segments: a scape, a pedicel, and a flagellum. The female antennae are slightly shorter than the male antennae. In both sexes, four types and nine subtypes of sensilla were observed: sensilla basiconica (SB1, SB2), sensilla campaniformia (SCa1, SCa2 and SCa3), sensilla coeloconica (SCo1, SCo2 and SCo3) and sensilla trichodea (ST). In addition, sensilla coeloconica (SCo1) are observed on the membrane of the top of the pedicel in Cercopidae for the first time. Sexual dimorphism mainly occurs in variation in the number of sensilla coeloconica (SCo2, SCo3) on the bulb-shaped portion of the flagellum and in the shape of sensilla basiconica (SB2). There are significantly more sensilla coeloconica in males than in females. The external structure and distribution of these sensilla are compared to those of other cercopids and possible functions of the antennal sensilla are discussed.

Morphological study of the antennal sensilla in Gerromorpha (Insecta: Hemiptera: Heteroptera)

The external morphology and distribution of the antennal sensilla of 21 species from five families of semiaquatic bugs (Gerromorpha) were examined using scanning electron microscopy. Nine main types were distinguished based on their morphological structure: sensilla trichoidea, sensilla chaetica, sensilla leaflike, sensilla campaniformia, sensilla coeloconica, sensilla ampullacea, sensilla basiconica, sensilla placoidea and sensilla bell-mouthed. The specific morphological structure of one type of sensilla (bell-mouthed sensilla) was observed only in Aquarius paludum. Several subtypes of sensilla are described, differentiated by number, location and type of sensillum characteristic for each examined taxon. The present study provides new data about the morphology and distribution of the antennal sensilla in Gerromorpha.

Structure and Sensilla of the Mouthparts of the Spotted Lanternfly Lycorma delicatula (Hemiptera: Fulgoromorpha: Fulgoridae), a Polyphagous Invasive Planthopper

Mouthparts are among the most important sensory and feeding structures in insects and comparative morphological study may help explain differences in feeding behavior and diet breadth among species. The spotted lanternfly Lycorma delicatula (White) (Hemiptera: Fulgoromorpha: Fulgoridae) is a polyphagous agricultural pest originating in China, recently established and becoming widespread in Korea, and more recently introduced into eastern North America. It causes severe economic damage by sucking phloem sap and the sugary excrement produced by nymphs and adults serves as a medium for sooty mold. To facilitate future study of feeding mechanisms in this insect, the fine-structural morphology of mouthparts focusing on the distribution of sensilla located on the labium in adult L. delicatula was observed using a scanning electron microscope. The mouthparts consist of a small cone-shaped labrum, a tubular labium and a stylet fascicle consisting of two inner interlocked maxillary stylets partially surrounded by two shorter mandibular stylets similar to those found in other hemipteran insects. The five-segmented labium is unusual (most other Fulgoromorpha have four segments) and is provided with several types of sensilla and cuticular processes situated on the apex of its distal labial segment. In general, nine types of sensilla were found on the mouthparts. Six types of sensilla and four types of cuticular processes are present on sensory fields of the labial apex. The proposed taxonomic and functional significance of the sensilla are discussed. Morphological similarities in the interlocking mechanism of the stylets suggest a relationship between Fulgoromorpha and Heteroptera.

Fine structure of sensory apparatus on the head of Cixiopsis punctatus

The external morphology of the heads of adult male and female Cixiopsis punctatus (Matsumura) (Hemiptera: Fulgoromorpha: Tropiduchidae) was studied using scanning electron microscopy. Eleven types of sensilla or sensory organs were identified: trichoid sensilla on the pedicel, scape, maxillae, and labium; campaniform sensilla on the antennal pedicel, antennal scape, maxillae, and labium; plate organs on the antennal pedicel; coeloconic sensilla in Bourgoin's organ and styloconic sensilla on the expanded flagellar base; Evans' organ and button-like sensilla on the maxillary plates; basiconic sensilla, peg sensilla, and coin-shaped sensilla on the labium. Styloconic sensilla on the expanded flagellar base and peg sensilla located between the dorsal sensory field and the opening of the maxillae and mandibles were first reported in Tropiduchidae. The external morphology, distribution, and abundance of sensilla located on antennae, maxillae, and labium in C. punctatus were illustrated.

External morphology of the mouthparts of the whitebacked planthopper Sogatella furcifera (Hemiptera: Delphacidae), with special reference to the sensilla

The whitebacked planthopper, Sogatella furcifera (Horváth), is a major pest of rice in Asia, with the adults and larvae sucking the phloem sap and affecting plant growth. The ultrastructural morphology of the mouthparts, with distribution of sensilla located on the maxillae and labium in adult S. furcifera was observed using scanning electron microscopy and illustrated, with a brief discussion of their taxonomic and putative functional significance. The gross mouthparts comprising an uppermost small cone-shaped labrum, a three-segmented labium with a deep longitudinal groove on the anterior side, and a stylet fascicle consisting of two mandibular and two maxillary stylets, are consistent with the conventional piercing-sucking type of mouth parts found in Hemiptera. The mandibles bear 5 teeth on the external convex region on the distal extremity. Smooth maxillary stylets, interlocked to form a larger food canal and a smaller salivary canal, are asymmetrical only in the internal position of longitudinal carinae and grooves. Two dendritic canals are also found in each maxilla and one in each mandible. The cross-section of the stylet fascicle is oval. The labial tip is a rosette shape. Two types of sensilla trichoides, two types of uniporous peg sensilla, two pairs of sensilla basiconica and a pair of subapical labial sensory organs have been detected at different locations on the labium, specifically the labial tip is divided into dorsal paired sensory fields with 9 pairs of uniporous peg sensilla and 1 pairs of dome-shaped sensilla, and ventral paired sensory fields with 2 pairs of sensilla basiconica.

Ultrastructure of antennal sensilla of a parasitoid fly, Pales pavida Meigen (Diptera: Tachinidae)

Pales pavida Meigen is obligated polyparasitic fly and important natural enemy of some most damaging forest or agricultural pests, and thus could contribute to the biological control of them. The external morphology of main olfactory organs in this tachinid was examined using stereopic microscopy and scanning electron microscopy, and types, distribution and density of sensilla were provided. The first two antennal segments, antennal scape and pedicel, are covered by microtrichiae and several mechanoreceptors. A pedicellar button is detected on antennal pedicel as well, after its separation with antennal funiculus. On antennal funiculus, five types of sensillar structures are observed including trichoid, basiconic, coeloconic, clavate sensilla and sensory pit with subtype II basiconic sensilla and a type of rarely described coeloconic-like sensilla in it, respectively. There are two specific sensillar characteristics of Pales pavida, two types of sensory pit on antennal funiculus and lower densities of all sensilla types than relatively monoparasitic species, which may serve as applicable evidence on their adaption to environment and lifestyle. Besides, the morphology of pedicellar button in tachinids is first addressed, armed with a discussion of their possible function.

Review of the genus Agria (Diptera, Sarcophagidae) from China

Agria mihalyii (Rohdendorf and Verves, 1978) is recorded from China for the first time, and both sexes are thoroughly documented using a combination of illustrations, photographs and scanning electron microscopy images. The generic affiliation is corroborated from an expanded definition of genus Agria Robineau-Desvoidy, 1830, and a key to males of the two known species from China is provided. The distribution of coeloconic sensilla on the male pre- and postgonite are shown to possess significant diagnostic and phylogenetic information in this genus.